This invention relates to a tubular body having integral branch tubes and is made of a single sheet metal solely by a deformation process and a method for producing the same to be used for forming, for instance, a distribution tank having an inlet and an outlet for a conductive medium flowing therethrough.
A distribution tank D for a car air conditioner produced according to the conventional method is shown in FIGS. 24-27. FIG. 24 is a front view, FIG. 25 is a bottom view and FIG. 26 is a rear view, respectively, of the distribution tank D. The main body 50 of the distribution tank D made of light metal is produced by an extrusion process. The main body 50 is formed with two main tubes 51 and 52 connected parallel with each other for flowing the cooling medium therethrough as shown by the FIGS. 25 and 26.
An inlet joint 53 for introducing the cooling medium in the tank D is connected to the left end of the main tube 51, and an outlet joint 54 for flowing out the cooling medium is connected to the right end of the main tube 52. Each end of the main tubes is blocked by stopcocks 55. In order that the cooling medium meanders across these two main tubes, dividing members 56 prepared by a separate process are provided at a plurality of positions to divide the space in both of the main tubes into a plurality of compartments.
A number of protruding branch tubes 57 are provided on the outer surfaces of the two main tubes 51 and 52 at intervals of a predetermined distance. The branch tubes 57 are provided for connecting thereto the ends of a number of the meandering tubes (not shown) for heat exchange.
The conventional method of producing the branch tubes 57 is explained with reference to FIG. 27. First, the main body 50 is extruded to form a shape the sectional view of which is shown in FIG. 27(a). Small square pillar bodies 50a are provided on the upper surfaces of the two main tubes 51 and 52 throughout the whole length of the two main tubes.
Next, the small square pillar bodies 50a are cut such that the small circular pillars 50b are left in the longitudinal direction of the main tubes at intervals of a predetermined distance. Then, small penetrating holes are created at the axis of each small circular pillar.
Thereafter, branch tubes 57 having desired inside diameter and length are created by forging in which a deformation process is applied to each small circular pillar 50b. Since this forging process cannot be conducted to many small circular pillars simultaneously, it needs to be separately conducted by small numbers in a plurality of times. In addition, within the category of the deformation process, the productivity of such a forging process is inferior to that of a press working process.
Since the production of the distribution tank D in the conventional method involves inefficient operations, such as cutting the small circular pillars 50b and conducting discontinuous forging processes several times, the production cost of the distribution tank D inevitably becomes high.